Despite its proven efficacy in reducing breast cancer mortality, little is known about the effectiveness of screening mammography in community practice. Of particular concern is its specificity outside academic medical settings and the implications of false positives on patient outcomes and costs of care. These are major issues for older women since surveys of mammography use have documented large increases in the rate of routine screening, especially for women over age 65. Monitoring trends in the use of screening mammography, assessing the accuracy of mammography in community practice and studying outcomes of routine screening in terms of follow-up procedures have been targeted by the Institute of Medicine as important topics for effectiveness research in breast cancer that might be initially addressed with Medicare claims data. Our current research is aimed at identifying potential uses and limitations of the claims data for mammography effectiveness research. Our goals for the competing renewal are to: 1) continue the validation studies by assessing the completeness of mammography in the claims; 2) examine correlates of the use and outcomes of screening mammograms; 3) describe changes in screening mammography outcomes over time (1993-1996) and 4) assess the effectiveness of mammography screening in community practice. Of particular interest is the comparison of completeness, use, outcomes and effectiveness for women age 65-74 versus women age 75 and older. Potential sources of missing mammograms in the claims will be examined by trying to link the radiology reports of Medicare beneficiaries who received mammograms in selected facilities to the Medicare claims data. The evaluation of use, outcomes and effectiveness will be conducted with the SEER-Medicare linked database and the sample of non-cancer controls. Measures of use and outcomes will be derived from these data and compared across the two age groups, the nine SEER areas and the four years from 1993 through 1996. The effect of screening mammography on breast cancer survival will be estimated for the two age groups by examining the screening practices from 1991-1994 for a cohort of SEER breast cancer cases diagnosed in 1995. Analyses will compare the size of tumor, stage and survival for women with different screening practices.